Hi Tiny,
But i cann't understand this.i think if the client side logic will be changed some days later
every client must download the new client but if we put it at server ,client is no need to do anything! am i right ? or i miss thing? i really want to know how they explain thire design who put bookflight() at client side.
If you only have primative operations on the server, then you can create different types of clients to connect to the server. For example, our client has no need to use the add() or delete() methods of the public Data interface. But we might (and probably would) want an administrative client that could delete old records, add new ones, and modify some exitsting records. If only business logic were on the server, we would then have to modify the server code as well as write the new client code.
This really all comes down to one fundamental question: What do you, the developer, feel are the responsibilites of the server? Of course, if we were writing a three-tier application this would be an easy question since the business logic would go in the middle tier. I would suggest that wherever you put the business logic, that you do it in such a way that it would be a simple matter to change the application to a three-tier application. Most of us have used the Facade
pattern on the client to translate the business logic into primative calls. That will allow you to create a middle tier at some point without too much alteration to the client and no alteration on the server. But it could work the same the other way around.
Hope this helps,
Michael Morris